The invention relates to catalysts useful for olefin polymerization. In particular, the invention relates to xe2x80x9csingle-sitexe2x80x9d catalysts that incorporate at least one indenoindolyl ligand.
Interest in single-site (metallocene and non-metallocene) catalysts continues to grow rapidly in the polyolefin industry. These catalysts are more reactive than Ziegler-Natta catalysts, and they produce polymers with improved physical properties. The improved properties include narrow molecular weight distribution, reduced low molecular weight extractables, enhanced incorporation of xcex1-olefin comonomers, lower polymer density, controlled content and distribution of long-chain branching, and modified melt rheology and relaxation characteristics.
While traditional metallocenes commonly include one or more cyclopentadienyl groups, many other ligands have been used. Putting substituents on the cyclopentadienyl, ring, for example, changes the geometry and electronic character of the active site. Thus, a catalyst structure can be fine-tuned to give polymers with desirable properties. xe2x80x9cConstrained geometryxe2x80x9d or xe2x80x9copen architecturexe2x80x9d catalysts have been described (see, e.g., U.S. Pat. No. 5,624,878). Bridging ligands in these catalysts lock in a single, well-defined active site for olefin complexation and chain growth. Other bridged complexes are stereospecific catalysts for xcex1-olefin polymerizations, providing a route to isotactic or syndiotactic polypropylene (see, for example, Herzog et al., J. Am. Chem. Soc. 118 (1996) 11988 and Mansel et al., J. Organometal. Chem. 512 (1996) 225).
Other known single-site catalysts replace cyclopentadienyl groups with one or more heteroatomic ring ligands such as boraaryl (see, e.g., U.S. Pat. No. 5,554,775), pyrrolyl, indolyl, (U.S. Pat. No. 5,539,124), or azaborolinyl groups (U.S. Pat. No. 5,902,866).
Substituted metallocenes, constrained-geometry catalysts, bridged complexes, and many heterometallocenes offer interesting advantages, including higher activity, control over. polyolefin properties, and stereoregular polymers. Variety, however, comes at a price: ligands used to make many of these catalysts require costly multi-step syntheses from expensive and often hard-to-handle starting materials and reagents.
In sum, there is a continuing need for single-site catalysts that can be prepared inexpensively and in short order. In particular, there is a need for catalysts that can be tailored to have good activities and to give polyolefins with desirable physical properties.
The invention is a single-site olefin polymerization catalyst. The catalyst comprises an activator and an organometallic complex. The organometallic complex comprises a Group 3 to 10 transition or lanthanide metal, M, and at least one indenoindolyl ligand that is xcfx80-bonded to M.
The invention includes a three-step method for making the organometallic complex. First, an indanone reacts with an aryl hydrazine in the presence of a basic, or acidic catalyst to produce an aryl hydrazone. Next, the aryl hydrazone is cyclized in the presence of an acidic catalyst to produce an indenoindole ligand precursor. Finally, the precursor is deprotonated, and the resulting anion reacts with a Group 3 to 10 transition or lanthanide metal source to produce the desired organometallic complex.
The invention provides a remarkably simple synthetic route to single-site olefin polymerization catalysts. Because many indanones and aryl hydrazines are commerically available or easily made, a wide variety of organometallic complexes that contain xcfx80-bonded indenoindolyl ligands can be expeditiously prepared. The ease and inherent flexibility of the synthesis puts polyolefin makers in charge of a new family of single-site catalysts.
Catalysts of the invention comprise an activator and an organometallic complex. The catalysts are xe2x80x9csingle sitexe2x80x9d in nature, i.e., they are distinct chemical species rather than mixtures of different species. They typically give polyolefins with, characteristically narrow molecular weight distributions (Mw/Mn less than 3) and good, uniform comonomer incorporation.
The organometallic complex includes a Group 3 to 10 transition or lanthanide metal, M. More preferred complexes include a Group 4 to 6 transition metal; most preferably the complex contains a Group 4 metal such as titanium or zirconium.
The organometallic complex also comprises at least one indenoindolyl ligand that is xcfx80-bonded to M. By xe2x80x9cindenoindole,xe2x80x9d we mean an organic compound that has both indole and indene rings. The five-membered rings from each are fused, i.e., they share two or more carbon atoms. Preferably, the rings are fused such that the indole nitrogen and the only sp3-hybridized carbon on the indenyl ring are xe2x80x9ctransxe2x80x9d to each other. Such is the case in an indeno[3,2-b]indole ring system such as: 
To identify how the rings are fused, the indene ring is numbered beginning with the xe2x80x94CH2xe2x80x94 group. The xe2x80x9cbxe2x80x9d side of the indole ring matches the xe2x80x9c3,2xe2x80x9d side of the indene. In accord with IUPAC Rule A-21.5, the order of the numbers (3,2) conforms to the direction of the base (indolyl) component (i.e., from a to b). Suitable ring systems include those in which the indole nitrogen and the sp3-hybridized carbon of the indene are beta to each other, i.e., they are on the same side of the molecule. This is an indeno[2,3-b]indole ring system: 
Any of the ring atoms can be unsubstituted or substituted with one or more groups such as alkyl, aryl, aralkyl, halogen, silyl, nitro, dialkylamino, diarylamino, alkoxy, aryloxy, thioether, or the like. Additional fused rings can be present, as long as an indenoindole moiety is present. For example, a benzo ring can be fused in the xe2x80x9ce,xe2x80x9d xe2x80x9cf,xe2x80x9d or xe2x80x9cgxe2x80x9d positions of either or both of the indene and indole rings, as in a benzo[f]indeno[3,2-b]indole system: 
Numbering of indenoindoles follows IUPAC Rule A-22. The molecule is oriented as shown above, and numbering is done clockwise beginning with the ring at, the uppermost right of the structure. Thus, 10-methyl-5H-indeno[3,2-b]indole is numbered as follows: 
Suitable indenoindole ligand precursors include, for example, 5,10-dihydroindeno[3,2-b]indole, 4,8,10-trimethyl-5H-indeno[3,2-b]indole, 4-tert-butyl-8-methyl-5,10-dihydroindeno[3,2b]indole, 4,8-dichloro-5,10-dihydroindeno[3,2-b]indole, 10-methylbenzo[f]-5H-indeno[3,2-b]indole, benzo[g]-5,10-dihydroindeno[3,2-b]indole, 5,10-dihydroindeno[3,2-b]benzo[e]indole, benzo[g]-5,10-dihydroindeno[3,2-b]benzo[e]indole, and the like.
The indenoindolyl ligand is generated by deprotonating a ligand precursor with a base to give an anionic ring system with a high degree of aromaticity (highly delocalized). Reaction of the anion with, e.g., a transition metal halide gives the desired organometallic complex. The indenoindolyl ligand is xcfx80-bonded to M in the complex.
The organometallic complex optionally includes one or more additional polymerization-stable, anionic ligands. Examples include substituted and unsubstituted cyclopentadienyl, fluorenyl, and indenyl, or the like, such as those described in U.S. Pat. Nos. 4,791,180 and 4,752,597, the teachings, of which are incorporated herein by reference. A preferred group of polymerization-stable ligands are heteroatomic ligands such as boraaryl, pyrrolyl, indolyl, quinolinyl, pyridinyl, and azaborolinyl as described in U.S. Pat. Nos. 5,554,775, 5,539,124, 5,637,660, and 5,902,866, the teachings of which are incorporated herein by reference. The organometallic complex also usually includes one or more labile ligands such as halides, alkyls, alkaryls, aryls, dialkylaminos, or the like. Particularly. preferred are halides, alkyls, and alkaryls (e.g., chloride, methyl, benzyl).
The indenoindolyl and/or polymerization-stable ligands can be bridged. For instance, a xe2x80x94CH2xe2x80x94, xe2x80x94CH2CH2xe2x80x94, or (CH3)2Si bridge can be used to link two indenoindolyl groups through the indolyl nitrogens. Groups that can be used to bridge the ligands include, for example, methylene, ethylene, 1,2-phenylene, and dialkyl silyls. Normally, only a single bridge is included. Bridging changes the geometry around the transition or lanthanide metal and can improve catalyst activity and other properties such as comonomer incorporation.
Exemplary organometallic complexes: 10H-indeno[3,2-b]indolyl titanium trichloride, 10H-indeno[3,2-b]indolyl zirconium trichloride, bis(3,7-dimethyl-10H-indeno[3,2-b]indolyl)titanium dimethyl, (3-tert-butyl-8,10-dimethylindeno[3,2-b]indolyl)zirconium trichloride, bis(10H-indeno[3,2-b]indoyl)zirconium dichloride, (10-phenyl-benzo[g]-indeno[3,2-b]indolyl)zirconium trichloride, (cyclopentadienyl)(10H-indeno[3,2-b]indolyl)zirconium dichloride, (8-quinolinoxy)(10H-indeno[3,2-b]indolyl)titanium dichloride, (1-methylborabenzene)(10H-indeno[3,2-b]indolyl)zirconium dimethyl, ansa-methylene-N,Nxe2x80x2-bis(10H-indeno[3,2-b]indolyl)zirconium dichloride, and the like.
The catalysts include an activator. Suitable activators ionize the organometallic complex to produce an active olefin polymerization catalyst. Suitable activators are well known in the art. Examples include alumoxanes (methyl alumoxane (MAO), PMAO, ethyl alumoxane, diisobutyl alumoxane), alkylaluminum compounds (triethylaluminum, diethyl aluminum chloride, trimethylaluminum, triisobutyl aluminum), and the like. Suitable activators include acid salts that contain non-nucleophilic anions. These compounds generally consist of bulky ligands attached to boron or aluminum. Examples include lithium tetrakis(pentafluorophenyl)borate, lithium tetrakis(pentafluorophenyl)aluminate, anilinium tetrakis(pentafluorophenyl)borate, and the like. Suitable activators also include organoboranes, which include boron and one or more alkyl, aryl, or aralkyl, groups. Suitable activators include substituted and unsubstituted trialkyl and triarylboranes such as tris(pentafluorophenyl)borane, triphenylborane, tri-n-octylborane, and the like. These and other suitable boron-containing activators are described in U.S. Pat. Nos. 5,153,157, 5,198,401, and 5,241,025, the teachings of which are incorporated herein by reference.
The amount of activator needed relative to the amount of organometallic complex depends on many factors, including the nature of the complex and activator, the desired reaction rate, the kind of polyolefin product, the reaction conditions, and other factors. Generally, however, when the activator is an alumoxane or an alkyl aluminum compound, the amount used will be within the range of about 0.01 to about 5000 moles, preferably from about 0.1 to about 500 moles, of aluminum per mole of M. When the activator is an organoborane or an ionic borate or aluminate, the amount used will be within the range of about 0.01 to about 5000 moles, preferably from about 0.1 to about 500 moles, of activator per mole of M.
If desired, a catalyst support such as silica or alumina can be used. However, the use of a support is generally not necessary for practicing the process of the invention.
The invention includes a three-step method for making the organometallic complex. In a first step, an indanone reacts with an aryl hydrazine in the presence of a basic or acidic catalyst to produce an aryl hydrazone by a known synthetic procedure.
Indanones are bicyclic compounds that have a cyclopentanone ring fused to a benzene ring. Both rings can be unsubstituted or substituted with alkyl, aryl, aralkyl, nitro, halide, thioether, or other groups. Additional fused rings can be present as long as an indanone moiety is present. Suitable indanones include, for example, 1-indanone, 2-indanone, 6-methylindan-1-one, 5-chloroindan-1-one, 6-nitroindan-2-one, benzo[f]indan-1-one, and the like, and mixtures thereof.
Aryl hydrazines are aromatic compounds that have a hydrazine (xe2x80x94NHNH2) group attached to an aromatic ring. They are often used and commercially available in the form of the acid salt, as in phenyl hydrazine hydrochloride. The aromatic ring of the aryl hydrazine can be substituted with the groups described above, and it can be fused to other rings. Suitable aryl hydrazines include, for example, phenyl hydrazine, p-tolyl hydrazine, m-tolyl hydrazine, p-chlorophenyl hydrazine, 1-naphthyl hydrazine, 2-naphthyl hydrazine, and the like, and mixtures thereof.
The ability to vary the substituents on the indanone and aryl hydrazine provides catalyst makers access to a diverse array of indenoindolyl ligands. This allows them to xe2x80x9cfine tunexe2x80x9d the activity of the corresponding organometallic complexes and, ultimately, the physical properties of the polyolefins. Because of the unique geometries of their active sites, some of the complexes should be valuable for making stereoregular polyolefins such as isotactic or syndiotactic polypropylene.
A wide variety of well-known acidic and basic compounds catalyze the reaction between the aryl hydrazine and the indanone. Examples include hydrochloric acid, acetic acid, sulfuric acid, p-toluenesulfonic acid, ammonia, triethylamine, sodium hydroxide, potassium hydroxide, sodium methoxide, sodium acetate, and the like.
Usually, the aryl hydrazine and the indanone are simply heated together with the catalyst, often with a reaction solvent, for a time needed to give the aryl hydrazone. The reaction product can be isolated and purified by conventional means (e.g., filtration, recrystallization), but more often, the aryl hydrazone is used in the next step without purification. A typical procedure is shown in J. Chem. Soc. (1952) 2225.
In step two, the aryl hydrazone cyclizes in the presence of an acidic catalyst in a Fischer indole reaction with elimination of ammonia to give an indenoindole ligand precursor. The reaction apparently involves an interesting [3,3]sigmatropic rearrangement (see J. March, Advanced Organic Chemistry, 2nd ed. (1977) 1054). A variety of acidic catalysts are suitable, including, for example, Lewis acids (zinc chloride, boron trifluoride), and protic acids (hydrochloric acid, acetic acid, p-toluenesulfonic acid). Usually, the crude aryl hydrazone is simply heated with the acidic catalyst for a brief period to cause the cyclization reaction. The reaction product is isolated and purified by any suitable method. In one method, the cyclization reaction mixture is poured into ice water and extracted into an organic solvent. The solution is dried, filtered, and evaporated to give the crude indenoindole ligand precursor, which can be further purified by recrystallization. In contrast to the previous step, it is preferred to purify this reaction product prior to using it in the next step.
In step three of the method, the ligand precursor is deprotonated by reacting it with at least one equivalent of a potent base such as lithium diisopropylamide, n-butyllithium, sodium hydride, a Grignard reagent, or the like. The resulting anion is reacted with a Group 3 to 10 transition or lanthanide metal source to produce an organometallic complex. The complex comprises the metal, M, and at least one, indenoindolyl ligand that is xcfx80-bonded to the metal. Any convenient source of the Group 3 to 10 transition or lanthanide metal can be used. Usually, the source is a complex that contains one or more labile ligands that are easily displaced by the indenoindolyl anion. Examples are halides (e.g., TiCl4, ZrCl4), alkoxides, amides, and the like. The metal source ban incorporate one or more of the polymerization-stable anionic ligands described earlier. The organometallic complex can be used xe2x80x9cas is.xe2x80x9d Often, however, the complex is converted to an alkyl derivative by treating it with an alkylating agent such as methyl lithium. The alkylated complexes are more suitable for use with certain activators (e.g., ionic borates).
Step three is normally performed by first generating the indenoindolyl anion at low temperature (0xc2x0 C. to xe2x88x92100xc2x0 C.), preferably in an inert solvent (e.g., a hydrocarbon). The anion is then usually added to a solution of the transition or lanthanide metal source at low to room temperature. After the reaction is complete, by-products and solvents are removed to give the desired transition metal complex. Examples A and B below illustrate typical catalyst syntheses.
The catalysts are particularly valuable for polymerizing olefins. Preferred olefins are ethylene and C3-C20 xcex1-olefins such as propylene, 1-butene, 1-hexene, 1-octene, and the like. Mixtures of olefins can be used. Ethylene and mixtures of ethylene with C3-C10 xcex1-olefins are especially preferred.
Many types of olefin polymerization processes can be used. Preferably, the process is practiced in the liquid phase, which can include slurry, solution, suspension, or bulk processes, or a combination of these. High-pressure fluid phase or gas phase techniques can also be used. The process of the invention is particularly valuable for solution and slurry processes.
The olefin polymerizations can be performed over a wide temperature range, such as about xe2x88x9230xc2x0 C. to about 280xc2x0 C. A more preferred range is from about 30xc2x0 C. to about 180xc2x0 C.; most preferred is the range from about 60xc2x0 C. to about 100xc2x0 C. Olefin partial pressures normally range from about 15 psia to about 50,000 psia. More preferred is the range from about 15 psia to about 1000 psia.
Catalyst concentrations used for the olefin polymerization depend on many factors. Preferably, however, the concentration ranges from about 0.01 micromoles per liter to about 100 micromoles per liter. Polymerization times depend on the type of process, the catalyst concentration, and other factors. Generally, polymerizations are complete within several seconds to several hours.
Examples 1-9 below illustrate typical olefin polymerizations using catalysts of the invention. As the examples show, the catalysts have good activity and give polymers with favorable melt-flow properties.